When creating a type 10: "unique answer with unknown" question, the "score" field is deactivated (which is good) for the "Don't know" choice, but the radio button to select the expected answer is still activated. This is misleading since it lets the user think that this is a valid choice, and this leads to really really weird behaviors if this button is ticked: I managed to get a score of 1 / 0 (yes, 1 points out of 0, not 0/1 ...) with this setup.